Linear Stapling Device With A Gap Locking Member

ABSTRACT

A method and a tool assembly maintain a tissue gap between distal portions of an anvil and a cartridge assembly of a stapling device. In embodiments, the tool assembly includes a locking member that is supported on one of the anvil and the cartridge assembly and is movable from an unlocked position to a locked position to secure distal portions of the anvil and the cartridge assembly together. In the locked position, the locking member is engaged with the distal portion of the other of the anvil and the cartridge assembly to maintain a tissue gap between the distal portion of the anvil and the cartridge assembly.

FIELD

This disclosure is directed to a surgical stapling device and, more particularly, to a linear surgical stapling device having a tool assembly that defines a tissue gap and includes a locking member to maintain the tissue gap during firing of the stapling device.

BACKGROUND

Surgical stapling devices are commonly used during a variety of surgical procedures to staple and/or cut tissue. Stapling and cutting of tissue can be accomplished more quickly using surgical stapling devices than can be accomplished using traditional suturing techniques. In addition, endoscopic stapling devices can be used to perform less invasive surgical procedures than possible using traditional suturing techniques. As such, the use of surgical stapling devices to perform certain surgical procedures to reduce patient trauma and improve patient recovery times is desirable.

Typically, linear endoscopic surgical stapling devices include a tool assembly that includes a staple cartridge and an anvil assembly that are movable in relation to each other between open and clamped positions. The staple cartridge defines a plurality of staple pockets that receive staples and the anvil assembly defines a plurality of staple deforming pockets. When the tool assembly is in the clamped position, the staple deforming pockets of the anvil assembly are aligned with the staple pockets of the staple cartridge such that legs of the staples are received and deformed within the staple deforming pockets when the stapling device is fired. The staple cartridge and the anvil assembly must be properly aligned to effect proper staple formation.

Generally, the staple cartridge and the anvil assembly have proximal ends that are secured to each other by a pivot member such that the staple cartridge and the anvil assembly can be pivoted from the open position in which distal ends of the staple cartridge and the anvil assembly are spaced from each other to the clamped position in which the staple cartridge and the anvil assembly are in juxtaposed alignment. During firing of the staples from the staple cartridge, forces on the staple cartridge and the anvil assembly for firing the staples tend to deflect the staple cartridge and anvil assembly outwardly away from each other. In certain stapling devices, a knife bar is provided that includes upper and lower beams that engage the anvil assembly and staple cartridge to minimize deflection of the anvil and cartridge assemblies during firing.

SUMMARY

One aspect of this disclosure is directed to a tool assembly including an anvil, a cartridge assembly, a clamping member, and a locking member. The anvil and the cartridge assembly each have a proximal portion and a distal portion. The proximal portion of the cartridge assembly is pivotally coupled to the proximal portion of the anvil. The clamping member is movable in relation to the anvil and the cartridge assembly between retracted and advanced positions to move the tool assembly between an open position and a clamped position. The locking member is supported on one of the anvil or the cartridge assembly and is movable from an unlocked position to a locked position. In the locked position, the locking member is engaged with the distal portion of the other of the anvil or the cartridge assembly to maintain a tissue gap between the distal portion of the anvil and the cartridge assembly.

In embodiments, the clamping member is positioned to move the locking member from the unlocked position to the locked position as the clamping member moves in relation to the anvil and the cartridge assembly.

In some embodiments, the locking member is supported on the cartridge assembly and includes an elongate member having a proximal portion and a distal portion, wherein the distal portion of the elongate member has an engagement portion that is engaged with the distal portion of the anvil when the locking member is in the locked position.

In certain embodiments, a tissue dissector is supported on the distal portion of the anvil and the tissue dissector defines a bore that is positioned to receive the engagement portion of the elongate member when the locking member is in the locked position.

In embodiments, the tissue dissector is angled towards the cartridge assembly when the tool assembly is in the clamped position and the engagement portion includes an angled finger that is received in the bore of the tissue dissector.

In some embodiments, the proximal portion of the locking member is engaged by the clamping member when the clamping member moves from its retracted position towards its advanced position.

In certain embodiments, the cartridge assembly includes a staple cartridge and the tool assembly includes a pusher that extends through a bore in a distal portion of the staple cartridge, wherein the pusher has a proximal portion and a distal portion engaged with the locking member.

In embodiments, a spring is positioned within the bore of the staple cartridge to urge the locking member towards its unlocked position and the pusher is movable to move the locking member to its locked position against a bias of the spring.

In some embodiments, a tissue dissector is supported on the distal portion of the anvil and defines a bore that is aligned with the locking member when the tool assembly is in the clamped position, wherein the locking member is received within the bore when the locking member is in the locked position.

In certain embodiments, the proximal portion of the pusher engages the clamping member as the clamping member moves between its retracted position and its advanced position.

In embodiments, the locking member includes a tissue dissector that is supported on the distal portion of the anvil.

In some embodiments, the tissue dissector is pivotally supported on the distal portion of the anvil.

In certain embodiments, a pusher has a proximal portion and a distal portion aligned with the locking member, wherein the pusher is movable to move the locking member from its unlocked position to its locked position.

In embodiments, the proximal portion of the pusher is engaged by the clamping member when the clamping member moves from its retracted position to its advanced position.

In some embodiments, a spring is positioned between the tissue dissector and the anvil to urge the locking member to its locked position.

Another aspect of this disclosure is directed to a method of maintaining a tissue gap between a cartridge assembly and an anvil, wherein the method includes moving an anvil of a stapling device in relation to a cartridge assembly of the stapling device from an open position to a clamped position; and moving a locking member of the stapling device from an unlocked position to a locked position to connect a distal portion of the anvil to a distal portion of the cartridge.

In embodiments, moving the locking member of the stapling device from the unlocked position to the locked position includes advancing the locking member along the cartridge assembly into engagement with the anvil.

In some embodiments, moving the locking member of the stapling device from the unlocked position to the locked position includes pivoting the locking about a pivot member supported on the anvil into engagement with a projection supported on the cartridge assembly.

In certain embodiments, moving the anvil of the stapling device in relation to the cartridge assembly of the stapling device from the open position to the clamped position includes advancing a clamping member along the anvil and the cartridge assembly.

In embodiments, moving the locking member of the stapling device from the unlocked position to the locked position includes engaging the locking member with the clamping member to move the locking member from its unlocked position to its locked position.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the disclosed linear surgical stapling device including a tool assembly locking member are described herein below with reference to the drawings, wherein:

FIG. 1 is a side perspective view of an exemplary embodiment of the disclosed stapling device including a tool assembly having a dissector tip with the tool assembly in an open position;

FIG. 2 is an enlarged view of the tool assembly of the stapling device shown in FIG. 1 in the open position;

FIG. 3 is a bottom perspective view of the tool assembly shown in FIG. 2 with the tool assembly in the open position;

FIG. 4 is an exploded perspective view of the tool assembly shown in FIG. 3;

FIG. 5 is a cross-sectional view along the longitudinal axis of the tool assembly shown in FIG. 3 with the tool assembly in the clamped position and the locking member in the unlocked position;

FIG. 6 is a cross-sectional view along the longitudinal axis of the tool assembly shown in FIG. 3 with the tool assembly in the clamped position and the locking member in the locked position;

FIG. 7 is a cross-sectional view taken along the longitudinal axis of another embodiment of the tool assembly in accordance with this disclosure with the tool assembly in the clamped position and the locking member in the unlocked position;

FIG. 8 is an enlarged view of the indicated area of detail shown in FIG. 7;

FIG. 9 is a cross-sectional view of the tool assembly shown in FIG. 7 with the tool assembly in the clamped position and the locking member in the locked position;

FIG. 10 is an enlarged view of the indicated area of detail shown in FIG. 9;

FIG. 11 is a side perspective view of a distal portion of another embodiment of a tool assembly in accordance with the disclosure with the tool assembly in the clamped position and the locking member in the unlocked position;

FIG. 12 is a side perspective view of the distal portion of the tool assembly shown in FIG. 11 with the tool assembly in the clamped position, the locking member in the unlocked position, and the dissecting tip shown in phantom;

FIG. 13 is a cross-sectional view taken along section lines 13-13 of FIG. 11;

FIG. 14 is an enlarged view of the indicated area of detail shown in FIG. 13 with the locking member in the unlocked position; and

FIG. 15 is an enlarged view of the indicated area of detail shown in FIG. 13 with the locking member moved to the locked position.

DETAILED DESCRIPTION

The disclosed surgical stapling device will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure in virtually any appropriately detailed structure.

In this description, the term “proximal” is used generally to refer to that portion of the device that is closer to a clinician, while the term “distal” is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term “clinician” is used generally to refer to medical personnel including doctors, nurses, and support personnel.

In FIG. 1, the surgical stapling device is illustrated generally as stapling device 10 and includes a handle assembly 12, an elongate body 14, and a staple reload 16. The elongate body 14 defines a longitudinal axis “X” and includes a proximal portion that is coupled to the handle assembly 12 and a distal portion that supports the staple reload 16. The staple reload 16 includes a proximal body portion 18 and a tool assembly 20. The proximal body portion 18 is releasably coupled to the distal portion of the elongate body 14. Alternately, the staple reload 16 and the elongate body 14 can be integrally formed such that the tool assembly 20 is fixedly attached to the elongate body 14.

The handle assembly 12 includes a housing 24 that defines a stationary handgrip 26 and supports a movable trigger 28 and a rotation knob 30. The rotation knob 30 is coupled to a distal portion of the housing 24 for rotation and supports the elongate body 14 such that rotation of the rotation knob 30 causes rotation of the elongate body 14 about the longitudinal axis “X”. The movable trigger 28 is supported by the housing 24 and can be pivoted in relation to the stationary handgrip 26 to actuate the tool assembly 20. In embodiments, the rotation knob also supports an articulation knob 34 that can pivot or rotate about an axis perpendicular to the longitudinal axis “X” to articulate the tool assembly 20 from a position aligned with the longitudinal axis “X” to a position misaligned with the longitudinal axis “X”. Although illustrated as being a manually operated handle assembly, it is envisioned that the handle assembly may be electrically or pneumatically powered, and may be adapted for use or coupled to a robotic surgical system.

FIGS. 2-4 illustrate the tool assembly 20 which includes an anvil 34 and a cartridge assembly 36. Each of the anvil 34 and the cartridge assembly 36 includes a distal portion and a proximal portion. The proximal portion of the anvil 34 is coupled to the proximal portion of the cartridge assembly 36 by a pivot member 38 such that the tool assembly 20 can pivot between an open position (FIG. 2) and a clamped position (FIG. 3).

In embodiments, the cartridge assembly 36 includes a channel 45 that defines a longitudinal slot 45 a (FIG. 3) and a staple cartridge 46 having a tissue contact surface 47. The staple cartridge 46 defines a plurality of staple pockets 48 and is received within the channel 45. In some embodiments, the staple cartridge 46 is adapted to be released from the channel 45 after firing of the stapling device 10 and replaced with a new or loaded staple cartridge 46. Each of the staple pockets 48 is configured and dimensioned to receive a staple (not shown). In embodiments, the staple cartridge 46 has a tissue guide portion 46 a that is angled away from the anvil 34 in the distal direction.

The anvil 34 defines a tissue engaging surface 34 a (FIG. 3) and includes a distal end portion that is angled from the tissue engaging surface 34 a of the anvil 34 towards the cartridge assembly 36 at an acute angle. The angled distal end portion of the anvil 34 forms a dissecting tip 50 that defines an opening 52. In embodiments, the dissecting tip 50 is spaced from the tissue guide portion 46 a of the staple cartridge 46 when the tool assembly 20 is in the clamped position and extends along an axis that is substantially parallel to an axis defined by the tissue guide portion 46 a. Alternately, the dissecting tip 50 may have other configurations.

The tool assembly 20 also includes a drive assembly 60 (FIG. 4). In embodiments, the drive assembly 60 of the tool assembly 20 includes a firing member 62 and clamping member 64. The firing member 62 includes spaced cam bars 66 that define an elongate slot 68. The cam bars 66 are coupled at their distal ends by an actuation sled 70. As known in the art, the cam bars 66 can be moved from a retracted position to an advanced position to advance the actuation sled 70 through the tool assembly 20 to eject staples (not shown) from the staple cartridge 46. The clamping member 64 may be coupled to a drive beam 71 that is received within the elongate slot 68 defined by the spaced cam bars 66.

In embodiments, the clamping member 64 is pressed or frictionally retained between the cam bars 66 and includes an upper beam 74, a lower beam 76, and a vertical strut 78 that extends between the upper and lower beams 74, 76. The upper beam 74 is positioned within a cutout 80 defined in the anvil 34 and is positioned to engage cam surfaces 82 on the anvil 34 such that distal movement of the clamping member 64 moves the anvil 34 about the pivot member 38 towards the cartridge assembly 36 from the open position (FIG. 2) to the clamped position (FIG. 5). The lower beam 76 is positioned to engage and move along a bottom surface of the cartridge assembly 36 to assist in moving the anvil 34 to the clamped position and to prevent outward movement of the cartridge assembly 36 during firing of the stapling device 10.

FIGS. 4-6 illustrate the tool assembly 20 including a locking member 86. The locking member 86 is positioned in the longitudinal slot 45 a of the channel 45 in abutment with a surface of the staple cartridge 46 and includes an elongated member having a proximal end 90 and a distal end 91 that defines an engagement portion 92. The proximal end 90 of the locking member 86 is positioned adjacent the clamping member 64 when the clamping member 64 is in a retracted position.

When the clamping member 64 is moved from its retracted position to its advanced position (FIG. 6), the clamping member 64 moves within the slot 80 in the anvil 34 and engages the proximal end 90 of the locking member 86 to advance the locking member 86 from a retracted position to an advanced position (FIG. 6). The distal end 91 of the locking member 86 is aligned with the opening 52 in the dissecting tip 50 of the anvil 34 such that when the locking member 86 is moved from its retracted position to its advanced position, the engagement portion 92 of the locking member 86 moves through the opening 52 to a locked position in locking engagement with the dissecting tip 50. Engagement of the locking member 92 with the dissecting tip 50 of the anvil 34 prevents outward movement of the anvil 34 in relation to the cartridge assembly 36 beyond a predetermined distance to set a pre-determined tissue gap “G” between the anvil 34 and cartridge assembly 36 at a distal end of the tool assembly 20.

In embodiments, the engagement portion 92 of the locking member 86 includes an angled finger that engages the distal portion of the staple cartridge 46 and the distal portion of the dissecting tip 50 to minimize outward movement of the anvil 34 in relation to the staple cartridge 46.

When the surgical stapling device 10 is actuated to move the tool assembly 20 from the open position (FIG. 3) to the clamped position (FIG. 5), the drive member 60 is initially moved in the direction indicated by arrow “A” in FIG. 6 to advance the clamping member 64 within the cutout 80 of the anvil 34 into engagement with the cam surfaces 82 (FIG. 5) of the anvil 34. Engagement of the clamping member 64 with the cam surfaces 82 on the anvil 34 moves the tool assembly 20 from the open position (FIG. 3) to the clamped position (FIG. 6). Since the clamping member 64 abuts the proximal end 90 of the locking member 86, movement of the clamping member 64 in the direction of arrow “A” moves the locking member 86 and the firing member 62 in the direction indicated by arrows “B” to advance the engagement portion 92 of the locking member 86 through the opening 52 in the dissecting tip 50 to lock the dissecting tip 50 to the distal portion of the cartridge assembly 36. Engagement between the engagement portion 92 of the locking member 86 and the dissecting tip 50 on the distal portion of the anvil 34 sets the tissue gap “G” (FIG. 6) defined between the anvil 34 and the staple cartridge 46 of the tool assembly 20.

When the clamping member 64 reaches the distal end of the slot 80 in the anvil 34, the clamping member 64 abuts a stop surface 80 a (FIG. 6) on the anvil 34 to prevent further distal movement of the clamping member 64 and the locking member 86. When the firing member 62 (FIG. 4) is advanced towards its distal-most position from the position shown in FIG. 6, the firing member 62 moves independently of the clamping member 64 and the locking member 86 to eject staples from the staple cartridge 46.

As shown, the locking member 86 is associated with the clamping member 64 such that movement of the clamping member 64 moves the tool assembly 20 to the clamped position and subsequently moves the locking member 86 to its locked position. It is envisioned that the association between the locking member 86 and the clamping member 64 can be modified to move the locking member 86 to its locked position as the tool assembly 20 moves to its clamped position.

As described above, the locking member 86 is moved to the locked position in response to movement of the clamping member 64. It is envisioned that a separate actuation mechanism can be used to move the locking member 86 to its locked position independently of the clamping member 64.

FIGS. 7-10 illustrate another embodiment of a locking member for setting the tissue gap of a tool assembly 120. The tool assembly 120 is similar to tool assembly 20 and will only be described in detail to describe differences between the two assemblies. The tool assembly 120 includes an anvil 134, a cartridge assembly 136, and a drive assembly 160. The anvil 134 includes a dissecting tip 150 that defines a bore 152. The cartridge assembly 136 includes a staple cartridge 146 that that supports a plurality of staples (not shown) and a pusher 186 that extends through the staple cartridge 146. The pusher 186 includes a proximal portion 190 and a distal portion 191.

The drive assembly 160 includes a firing member 162 and a clamping member 164 that are as described above in regard to the firing member 62 and the clamping member 64. The clamping member 164 is aligned with the proximal portion 190 of the pusher 186 such that movement of the clamping member 164 from a retracted position towards an advanced position (FIG. 9) moves the pusher 186 from a retracted position to an advanced position.

The staple cartridge 146 includes a locking member 192 that extends through a stepped bore 194 (FIG. 8) defined in the staple cartridge 146. The locking member 192 includes a proximal portion that is engaged with the distal portion of the pusher 186 such that distal movement of the pusher 186 causes distal movement of the locking member 192. When the tool assembly 120 is in a clamped position (FIG. 7), the locking member 192 is aligned with the bore 152 in the dissecting tip 150. A spring 196 is positioned within the stepped bore 194 of the staple cartridge 136 to urge the pin 192 to its retracted position in which a distal end of the locking member 192 is spaced from the bore 152 in the dissecting tip 150.

In embodiments, the locking member 192 may be in the form of an elongate pin that includes a flange 197. In embodiments, the flange 197 is positioned to engage a shoulder 198 that is defined by a wall defining the stepped bore 194 to prevent proximal movement of the locking member 186 through the stepped bore 194 of the staple cartridge 146. In embodiments, the elongate pin 192 includes a head 199 and the spring 196 is positioned between the shoulder 198 and the head 199 to urge the elongate pin 192 proximally within the stepped bore 194.

FIGS. 9 and 10 illustrate the tool assembly 120 as the clamping member 164 is advanced in the direction indicated by arrows “D” to move the anvil 134 and the cartridge assembly 136 from the open position to the clamped position (FIG. 9). The tool assembly 120 functions in a similar manner to the tool assembly 20. More specifically, when the clamping member 164 is advanced within the slot 180 defined in the anvil 134, the clamping member 164 engages cam surfaces 182 to first move the anvil 134 towards the cartridge assembly 136 to move the tool assembly 120 from the open position to the clamped position. As the clamping member 164 advances, the pusher 186 which is engaged with the clamping member 164 is advanced. The distal end of the pusher 186 is engaged with the locking member 192 such that advancement of the pusher 186 advances the locking member 192 against the bias of the spring 196 into the bore 152 in the dissector tip 150 to lock the distal end of the cartridge assembly 136 in relation to the distal end of the anvil 134.

As described above, the locking member 192 is moved to the locked position in response to movement of the clamping member 164. It is envisioned that a separate actuation mechanism can be used to move the locking member 192 to its locked position independently of the clamping member 164.

FIGS. 11-15 illustrate another embodiment of a locking member for setting the tissue gap of a tool assembly 220. The tool assembly 220 is similar to tool assemblies 20 and 120 and will only be described in detail to describe differences between the different assemblies. The tool assembly 220 includes an anvil 234, a cartridge assembly 236, and a drive assembly 260. The anvil 234 includes a dissecting tip 250 that defines a bore 252 and is pivotably supported on the distal portion of the anvil 234 about a pivot member 234 a (FIG. 12).

The cartridge assembly 236 includes a staple cartridge 246 that that supports a plurality of staples (not shown). The drive assembly 260 includes a firing member 262 and a clamping member 264 that are as described above in regard to the firing members 62, 162 and the clamping members 64, 164.

The anvil 234 supports a pusher 286 that has a proximal portion 290 aligned with the clamping member 264 (FIG. 13) and a distal portion 291 that is aligned with a proximal surface of the dissector tip 250 at a position above the pivot member 234 a as viewed in FIG. 13. When the clamping member 264 is moved from its retracted position (FIG. 13) towards its advanced position, the clamping member 264 engages and moves the pusher 286 from a retracted position to an advanced position. As the pusher 286 moves towards its advanced position, the distal portion 291 of the pusher 286 engages and pivots the tissue dissector 250 about the pivot member 234 a downwardly, as viewed in FIG. 15, towards its locked position engaged with a distal portion 296 of the staple cartridge 246. In embodiments, the distal end 299 (FIG. 15) of the distal portion 291 of the pusher 286 may be tapered to assist movement of the tissue dissector 250 towards its locked position.

The distal portion 296 of the staple cartridge 246 includes projection 296 that is received within the bore 252 of the tissue dissector 250 when the tissue dissector 252 is pivoted to its locked position. In embodiments, a spring 298 is positioned between the proximal surface of the tissue dissector 250 and the distal portion of the anvil 234 to urge the tissue dissector 250 towards its unlocked position (FIG. 14).

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of this disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A tool assembly comprising: an anvil having a proximal portion and a distal portion; a cartridge assembly having a proximal portion and a distal portion, the proximal portion of the cartridge assembly pivotally coupled to the proximal portion of the anvil; a clamping member movable in relation to the anvil and the cartridge assembly between retracted and advanced positions to move the tool assembly between an open position and a clamped position; and a locking member supported on one of the anvil or the cartridge assembly, the locking member movable from an unlocked position to a locked position, wherein in the locked position, the locking member is engaged with the distal portion of the other of the anvil or the cartridge assembly to maintain a tissue gap between the distal portion of the anvil and the cartridge assembly.
 2. The tool assembly of claim 1, wherein the clamping member is positioned to move the locking member from the unlocked position to the locked position as the clamping member moves in relation to the anvil and the cartridge assembly.
 3. The tool assembly of claim 1, wherein the locking member is supported on the cartridge assembly and includes an elongate member having a proximal portion and a distal portion, the distal portion of the elongate member having an engagement portion that is engaged with the distal portion of the anvil when the locking member is in the locked position.
 4. The tool assembly of claim 3, further including a tissue dissector supported on the distal portion of the anvil, the tissue dissector defining a bore positioned to receive the engagement portion of the elongate member when the locking member is in the locked position.
 5. The tool assembly of claim 1, wherein the tissue dissector is angled towards the cartridge assembly when the tool assembly is in the clamped position and the engagement portion includes an angled finger that is received in the bore of the tissue dissector.
 6. The tool assembly of claim 3, wherein the proximal portion of the locking member is engaged by the clamping member when the clamping member moves from its retracted position towards its advanced position.
 7. The tool assembly of claim 1, wherein the cartridge assembly includes a staple cartridge, and the tool assembly further includes a pusher that extends through a bore in a distal portion of the staple cartridge, the pusher having a proximal portion and a distal portion, the distal portion engaged with the locking member.
 8. The tool assembly of claim 7, further including a spring positioned within the bore of the staple cartridge, the spring positioned to urge the locking member towards its unlocked position, the pusher movable to move the locking member to its locked position against a bias of the spring.
 9. The tool assembly of claim 8, further including a tissue dissector supported on the distal portion of the anvil, the tissue dissector defining a bore that is aligned with the locking member when the tool assembly is in the clamped position, the locking member received within the bore when the locking member is in the locked position.
 10. The tool assembly of claim 9, wherein the proximal portion of the pusher engages the clamping member as the clamping member moves between its retracted position and its advanced position.
 11. The tool assembly of claim 1, wherein the locking member includes a tissue dissector supported on the distal portion of the anvil.
 12. The tool assembly of claim 11, wherein the tissue dissector is pivotally supported on the distal portion of the anvil.
 13. The tool assembly of claim 12, further including a pusher having a proximal portion and a distal portion aligned with the locking member, the pusher being movable to move the locking member from its unlocked position to its locked position.
 14. The tool assembly of claim 13, wherein the proximal portion of the pusher is engaged by the clamping member when the clamping member moves from its retracted position to its advanced position.
 15. The tool assembly of claim 14, further including a spring positioned between the tissue dissector and the anvil, the spring positioned to urge the locking member to its locked position.
 16. A method of maintaining a tissue gap between a cartridge assembly and an anvil, the method comprising: moving an anvil of a stapling device in relation to a cartridge assembly of the stapling device from an open position to a clamped position; moving a locking member of the stapling device from an unlocked position to a locked position to connect a distal portion of the anvil to a distal portion of the cartridge assembly.
 17. The method of claim 16, wherein moving the locking member of the stapling device from the unlocked position to the locked position includes advancing the locking member along the cartridge assembly into engagement with the anvil.
 18. The method of claim 16, wherein moving the locking member of the stapling device from the unlocked position to the locked position includes pivoting the locking about a pivot member supported on the anvil into engagement with a projection supported on the cartridge assembly.
 19. The method of claim 16, wherein moving the anvil of the stapling device in relation to the cartridge assembly of the stapling device from the open position to the clamped position includes advancing a clamping member along the anvil and the cartridge assembly.
 20. The method of claim 19, wherein moving the locking member of the stapling device from the unlocked position to the locked position includes engaging the locking member with the clamping member to move the locking member from its unlocked position to its locked position. 